1. Field of the Invention
The present invention relates generally to magnetic tape recording/reproducing apparatus such as video tape recorders (VTR), and more particularly to a support mechanism incorporated in such apparatus for supporting a tension pole used for the adjustment of the tension on a magnetic tape.
2. Description of the Prior Art
In a video tape recorder (VTR), a segment of the magnetic tape between a supply reel and a take-up reel in a tape cassette is withdrawn from the tape cassette by a loading pole when the tape cassette is loaded. The tape segment thus withdrawn forms a traveling path (hereinafter referred to as "tape path") extending around a drum over a predetermined angular range, the drum having a rotating magnetic head. The VTR includes a tension arm pivotally supported between a supply reel carrier and the drum and disposed adjacent to the tape path. The tension arm has a tension pole upstanding from the distal end thereof. In response to the loading action of the tape cassette, the tension arm turns in a direction to move the tension pole from the unloading position in which the tension pole is disposed in a recess in a front lower portion of the tape cassette, to a position outside the tape cassette. In the recording and reproducing modes, the tension pole is held in contact with the magnetic tape segment running between the supply reel and the drum. During that time, the tension pole changes its position in response to changes of the tension on the magnetic tape. The position or the movement of the tension pole is controlled by adjusting a brake force which is exerted on the supply reel carrier by a brake band provided on the proximal end of the tension arm. Thus, the tension on the magnetic tape is kept constant at all times.
One such VTR is disclosed in Japanese Patent Laid-open Publication No. 63-225949.
In the disclosed VTR, the pivot axis of the tension arm is fixed to a chassis. This fixed attachment of the pivot axis requires the tension arm to be disposed in a position far distant from a range of fluctuation of the tape path and a path of movement of the loading pole, in view of the fluctuation of the tape path and the movement of the loading pole. This arrangement of the tension arm considerably restricts the positioning of other component parts. Consequently, the conventional VTR (i.e. the magnetic tape recording/reproducing apparatus) is low in degree of freedom of the design choice and has a large tape traveling system.